Vehicle guidance system

ABSTRACT

A vehicle guidance system is provided with a controller configured to receive input indicative of a relative position between a charging port and a charging pad, and to provide output indicative of a distance vector therebetween in response to the input. An interface communicates with the controller and is configured to display a base element representing the charging port and target element representing the charging pad positioned relative to each other according to the distance vector.

TECHNICAL FIELD

One or more embodiments relate to a vehicle guidance system fordetermining vehicle position relative to an external power supply forfacilitating vehicle battery charging.

BACKGROUND

Battery electric vehicles (BEVs) and plug-in hybrid electric vehicles(PHEVs) may be connected to an external power supply for charging avehicle battery. Such vehicles typically include a charge cord thatextends from an external power supply and is physically connected to avehicle charging port to facilitate charging of the vehicle battery.However, such charge cords are prone to operator error. For example, ifthe user fails to properly connect the charge cord, or forgets toconnect the charge cord altogether, then the battery will not becharged. Further the user may damage the charge cord or the vehicle ifhe or she forgets to disconnect the charge cord before driving away fromthe external power supply. Additionally, the charge cord must be storedin a secure location when not in use. For example, the charge cord maybe damaged if the user leaves the charge cord on the ground andinadvertently drives over it.

Vehicles may include sensors for providing signals that indicate thelocation of external objects relative to the vehicle. For example, somevehicles include rear sensors for detecting objects behind the vehiclewhen the vehicle is in reverse gear and “backing up”. Other vehiclesinclude sensors for detecting objects in proximity to the vehicle, andthe vehicle includes a controller for controlling the steering of thevehicle while the vehicle is backing up or parallel parking.

SUMMARY

In one embodiment, a vehicle guidance system is provided with acontroller configured to receive input indicative of a relative positionbetween a charging port and a charging pad, and to provide outputindicative of a distance vector therebetween in response to the input.An interface communicates with the controller and is configured todisplay a base element representing the charging port and target elementrepresenting the charging pad positioned relative to each otheraccording to the distance vector.

In another embodiment, a vehicle guidance system is provided with asensor array having at least two sensors and a microcontroller. Eachsensor is configured to provide output indicative of a time when asignal was received from a transmitter. The microcontroller communicateswith the sensors and is configured to provide output indicative of anangular direction between the sensor array and the transmitter. Whereinthe angular direction is based on a difference between the times whenthe signals were received.

In yet another embodiment, a vehicle is provided with a charging portthat is configured to receive an inductive charging current. The vehicleis also provided with at least two sensor arrays, and a controller. Eachsensor array is configured to provide output indicative of an angulardirection between the sensor array and a transmitter remote from thevehicle. The controller is configured to provide output indicative of adistance vector between the charging port and the transmitter based onthe output indicative of the angular direction between the sensor arraysand transmitter. An interface communicates with the controller and isconfigured to display a base element representing the charging port anda target element representing a charging pad positioned relative to eachother according to the distance vector.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a vehicle guidance system according to oneor more embodiments and illustrated located within a partiallyfragmented structure having an external power supply;

FIG. 2 is a schematic diagram further illustrating the vehicle guidancesystem of FIG. 1, and illustrated with the external power supply;

FIG. 3 is a front perspective view of a user interface of the vehicleguidance system of FIG. 1;

FIG. 4 is another schematic diagram of the vehicle guidance system ofFIG. 1, illustrated with the external power supply;

FIG. 5 is a partial view of the vehicle guidance system of FIG. 4,illustrated with an enlarged sensor array and a central axis;

FIG. 6 is a partial view of the vehicle guidance system of FIG. 4,illustrated rotated about the central axis;

FIG. 7 is a diagram further illustrating the vehicle guidance system ofFIG. 6;

FIG. 8 is a flow chart illustrating a method for determining vehicleposition relative to an external power supply according to one or moreembodiments;

FIG. 9 is an enlarged view of the user interface of FIG. 3 according toone or more embodiments and illustrating a non-aligned vehicle position;

FIG. 10 is another enlarged view of the user interface of FIG. 3,illustrating an aligned vehicle position;

FIG. 11 is a schematic diagram of a vehicle guidance system according toanother embodiment; and

FIG. 12 is a flow chart illustrating a method for conveying vehicledistance status and charging status to a user according to one or moreembodiments.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

With reference to FIG. 1, a vehicle guidance system is illustrated inaccordance with one or more embodiments and is generally referenced bynumeral 20. The guidance system 20 is depicted within a vehicle 22. Theguidance system 20 includes a guidance controller 24 and a userinterface 26 that are in communication with each other. The controller24 receives input signals and determines an instantaneous position ofthe vehicle 22 relative to an external power supply 28 and a chargingstatus. The controller 24 transmits this information to the userinterface 26, which in turn conveys the information to the driver. Thedriver uses this information as a guide to align the vehicle 22 to theexternal power supply 28.

The external power supply 28 includes a power source 30 and a chargingpad 32. The external power source 30 may include a device for harnessingrenewable resources, such as sunlight and wind power. In the illustratedembodiment, the power source 30 is a solar panel that converts solarpower (sunlight) into direct current (DC) electrical power. Otherembodiments of the power source 30 include a wind turbine (not shown)for converting wind power into electric power. An external battery 31 isdisposed between the power source 30 and the charging pad 32 for storingthe DC power. In one embodiment, the external battery 31 is a recycledhigh voltage battery from a HEV, PHEV or BEV. Additionally, an inverter33 is connected between the external battery 31 and the charging pad 32for converting the DC power to alternating current (AC). Alternativelythe external power supply 28 may connect to the power grid (not shown),where the power source 30 represents an AC power source, or connectionto the grid (not shown).

The vehicle 22 is configured for inductive charging. The vehicle 22includes a charging port 34 that is mounted to an external bottomsurface of the vehicle, according to one or more embodiments. Thecharging port 34 is aligned with the charging pad 32 for receivingelectrical energy. Inductive charging does not require physical contactbetween the charging port 34 and charging pad 32, which limits some ofthe problems associated with charge cords and physical connections.However, the charging port 34 and charging pad 32 must be generallyclose in proximity to each other for efficient inductive charging. Sincethe charging port 34 is not visible from the driver's seat, it isdifficult for the driver to align the charging port 34 to the chargingpad 32 without a guide or some type of feedback.

The guidance system 20 conveys vehicle position information to the userso that the user can align the charging port 34 to the charging pad 32.At least one embodiment of the guidance system 20 is contemplated for avehicle 22 having a park-assist feature whereby other vehicle systemsalign the charging port 34 to the charging pad 32 in response to vehicleposition information provided by the guidance system 20. The chargingpad 32 may be secured in a fixed position. Alternatively, the pad 32 maybe coupled to an actuator 35 to move towards the charging port 34.

FIG. 2 is a schematic diagram further illustrating the vehicle guidancesystem 20 according to one or more embodiments. The illustratedembodiment depicts the vehicle 22 as a battery electric vehicle (BEV),which is an all-electric vehicle propelled by one or more electricmotors 36 without assistance from an internal combustion engine (notshown). The motor 36 receives electrical power and provides mechanicalrotational output power. The motor 36 is mechanically connected to agearbox 38 for adjusting the output torque and speed of the motor 36 bya predetermined gear ratio. The gearbox 38 is connected to a set ofdrive wheels 40 by an output shaft 42. Other embodiments of the vehicle22 include multiple motors (not shown) for propelling the vehicle 22.The motor 36 may also function as a generator for converting mechanicalpower into electrical power. A high voltage bus 44 electrically connectsthe motor 36 to an energy storage system 46 through an inverter 48. Thehigh voltage bus 44 is illustrated as a solid line in FIG. 2.

The energy storage system 46 includes a main battery 50 and a batteryenergy control module (BECM) 52, according to one or more embodiments.The main battery 50 is a high voltage battery that is capable ofoutputting electrical power to operate the motor 36. According to one ormore embodiments, the main battery 50 may be a battery pack made up ofseveral battery modules. Each battery module may contain a plurality ofbattery cells. The battery cells may be air cooled using existingvehicle cabin air. The battery cells may also be heated or cooled usinga fluid coolant system. The BECM 52 acts as a controller for the mainbattery 50. The BECM 52 may also include an electronic monitoring systemthat manages temperature and state of charge of each of the batterycells. Other embodiments of the vehicle 22 contemplate different typesof energy storage systems, such as capacitors and fuel cells (notshown).

The motor 36, the gearbox 38, and the inverter 48 may collectively bereferred to as a transmission 54. A vehicle controller 56 controls thecomponents of the transmission 54, according to one embodiment. Althoughit is shown as a single controller, the vehicle controller 56 mayinclude multiple controllers that may be used to control multiplevehicle systems. For example, the vehicle controller 56 may be a vehiclesystem controller/powertrain control module (VSC/PCM). In this regard,the PCM portion of the VSC/PCM may be software embedded within theVSC/PCM, or it can be a separate hardware device. The vehicle controller56 and the controller 24, generally include any number ofmicroprocessors, ASICs, ICs, memory (e.g., FLASH, ROM, RAM, EPROM and/orEEPROM) and software code to co-act with one another to perform a seriesof operations. The vehicle controller 56 communicates with othercontrollers (e.g., BECM 52) over a hardline vehicle connection 58 usinga common bus protocol (e.g., CAN).

According to one or more embodiments, the transmission 54 includes atransmission control module (TCM) 60 configured to coordinate specificcomponents within the transmission 54, such as the motor 36 and/or theinverter 48. The TCM 60 may communicate with the vehicle controller 56over the CAN bus 58. The TCM 60 may include a motor controller formonitoring, among other things, the position, speed, power consumptionand temperature of the motor 36. Using this information and a throttlecommand by the driver, the motor controller and the inverter 48 mayconvert the direct current (DC) voltage supply by the main battery 50into signals that can be used to drive the motor 36. Some or all ofthese various controllers can make up a control system, which, forreference purposes, may be the vehicle controller 56. Althoughillustrated and described in the context of the vehicle 22, which is aBEV, it is understood that embodiments of the present application may beimplemented on other types of vehicles, such as those powered by aninternal combustion engine, either alone or in addition to one or moreelectric machines (e.g., HEVs, PHEVs, etc.).

In one or more embodiments, the vehicle 22 is configured for automaticpropulsion control. For example, in one embodiment the vehicle 22 isconfigured as a BEV, and includes a park-assist feature whereby the TCM60 controls the output torque of the motor 36 in response to the vehicleposition information provided by the guidance system 20, for propellingthe vehicle 22. In another embodiment the vehicle 22 is configured as anHEV, or PHEV, and includes a park-assist feature whereby the vehiclecontroller 56 controls the engine (not shown) to propel the vehicle 22in response to the vehicle position information provided by the guidancesystem 20.

The vehicle 22 includes a climate control system 62 for heating andcooling various vehicle components. The climate control system 62includes a high voltage positive temperature coefficient (PTC) electricheater 64 and a high voltage electric HVAC compressor 66, according toone or more embodiments. The PTC 64 may be used to heat coolant thatcirculates to a passenger car heater and to the main battery 50. Boththe PTC 64 and the HVAC compressor 66 may draw electrical energydirectly from the main battery 50. The climate control system 62 mayinclude a controller (not shown) for communicating with the vehiclecontroller 56 over the CAN bus 58. The on/off status of the climatecontrol system 62 is communicated to the vehicle controller 56, and canbe based on, for example, the status of an operator actuated switch, orthe automatic control of the climate control system 62 based on relatedfunctions such as window defrost.

The vehicle 22 includes a secondary battery 68, such as a typical12-volt battery, according to one embodiment. The secondary battery 68may be used to power the vehicle's various other accessories,headlights, and the like (collectively referred to herein as accessories70). A DC-to-DC converter 72 may be electrically interposed between themain battery 50 and the secondary battery 68. The DC-to-DC converter 72adjusts, or “steps down” the voltage level to allow the main battery 50to charge the secondary battery 68. A low voltage bus 74 electricallyconnects the DC-to-DC converter 72 to the secondary battery 68 and theaccessories 70. The low voltage bus 74 is illustrated as a solid line inFIG. 2.

The vehicle 22 includes an AC charger 76 for charging the main battery50. The AC charger 76 is connected to the charging port 34 for receivingAC power from the external power supply 28. The AC charger 76 includespower electronics used to convert, or “rectify” the AC power receivedfrom the external power supply 28 to DC power for charging the mainbattery 50. The AC charger 76 is configured to accommodate one or moreconventional voltage sources from the external power supply 28 (e.g.,110 volt, 220 volt, etc.).

The charging port 34 is aligned with the charging pad 32 for receivingelectrical power. The external power supply 28 includes a primary coil78 that is disposed in the charging pad 32 and connected to the powersource 30. The charging port 34 includes a secondary coil 80 which isconnected to the AC charger 76. The power source 30 supplies the primarycoil 78 with a current which establishes a magnetic field (not shown)about the primary coil 78. The secondary coil 80 may beelectromagnetically coupled to the primary coil 78, by aligning thecharging port 34 with the charging pad 32, and placing the secondarycoil 80 within the magnetic field. This magnetic field induces a currentin the secondary coil 80 for charging the main battery 50, which isreferred to as inductive charging.

The external power supply 28 includes an external controller 82 forcommunicating with one or more controllers of the vehicle 22, accordingto one or more embodiments. The external controller 82 may communicatewirelessly, for example using radio-frequency (RF), infrared (IF) orsonar communication. For example, in one embodiment, the externalcontroller 82 communicates with the controller 24 of the guidance system20 using RF communication; and the controller 24 communicates with thevehicle controller 56 by a hardline electrical connection. In anotherembodiment, the charging port 34 includes a microcontroller 102 (shownin FIG. 5) for communicating with both the external controller 82 andthe controller 24. Wireless communication is represented by dashedsignal lines, in FIG. 2.

The external controller 82 communicates with the charging pad 32 forcontrolling the electrical power provided to the vehicle 22. In oneembodiment, the external controller 82 communicates with switches (notshown, e.g., IGBTs) between the source 30 and the primary coil 78 toonly allow current to flow if certain conditions are met. For example,the external controller 82 may prevent charging unless the vehiclecontroller 56 has requested charging, or unless the charging port 34 iswithin a predetermined distance from the charging pad 32.

Also shown in FIG. 2 are simplified schematic representations of adriver controls system 84, a power steering system 86, and a navigationsystem 88. The driver controls system 84 includes braking, accelerationand gear selection (shifting) systems (all not shown). The brakingsystem may include a brake pedal, position sensors, pressure sensors, orsome combination thereof, as well as a mechanical connection to thevehicle wheels, such as the primary drive wheels 40, to effect frictionbraking. The braking system may also be configured for regenerativebraking, wherein braking energy may be captured and stored as electricalenergy in the main battery 50. The acceleration system may include anaccelerator pedal having one or more sensors, which, like the sensors inthe braking system, may provide information such as throttle input tothe vehicle controller 56. The gear selection system may include ashifter for manually selecting a gear setting of the gearbox 38. Thegear selection system may include a shift position sensor for providingshifter selection information (e.g., PRNDL) to the vehicle controller56.

In one or more embodiments, the power steering system 86 includes asteering actuator (not shown) for automatic steering control. Thesteering actuator is coupled to the drive wheels 40 for adjusting asteering angle (not shown) of each wheel 40 in response to an inputsignal. For example, the vehicle 22 may include a park-assist featurewhereby the vehicle controller 56, or some other controller, controlsthe steering actuator to steer the vehicle 22 in response to the vehicleposition information provided by the guidance system 20.

The navigation system 88 may include a navigation display, a globalpositioning system (GPS) unit, a navigation controller and inputs (allnot shown) for receiving destination information or other data from adriver. These components may be unique to the navigation system 88 orshared with other systems. For example, in one or more embodiments thenavigation system 88 and the guidance system 20 both use a common userinterface 26. The navigation system 88 may also communicate distanceand/or location information associated with the vehicle 22, its targetdestinations, or other relevant GPS waypoints.

The vehicle guidance system 20 provides information to the driverregarding the position of the vehicle 22 relative to the external powersupply 28, and the charging status. The vehicle controller 56 receivesinput signals that are indicative of current operating conditions of thevehicle 22. For instance, the vehicle controller 56 may receive inputsignals from the BECM 52, the transmission 54 (e.g., motor 36 and/orinverter 48), the climate control system 62, the driver controls system84, the power steering system 86, or the like. The vehicle controller 56provides output to the controller 24 such that the user interface 26conveys vehicle position information, charging status or otherinformation relating to the operation of the vehicle 22 to a driver.

Referring to FIG. 3, the user interface 26 conveys information, such asvehicle position and charging status, to the driver. The user interface26 is located in a central portion of a dashboard 90 (“centerstack”)according to one or more embodiments. Moreover, the user interface 26may be part of another display system, such as the navigation system 88,or may be part of a dedicated guidance system 20. The user interface 26may be a liquid crystal display (LCD), a plasma display, an organiclight emitting display (OLED), or any other suitable display. The userinterface 26 may include a touch screen or one or more buttons (notshown), including hard keys or soft keys, located adjacent the userinterface 26 for effectuating driver input. Other operator inputs knownto one of ordinary skill in the art may also be employed withoutdeparting from the scope of the present application. The user interface26 is located within an instrument panel 92, according to anotherembodiment. The user interface 26 may be a digital display, or anindicia 94 that is illuminated by an underlying light source in responseto signals from the controller 24. Alternatively, the user interface 26may be an image that is projected in front the driver (not shown).

FIG. 4 illustrates a schematic top view of the vehicle guidance system20 according to at least one embodiment. The guidance system 20determines the position of the charging port 34 relative to the chargingpad 32, and conveys a visual representation of this position to thedriver via the user interface 26 (shown in FIG. 3).

The external power supply 28 includes a transmitter, such as a beacon96, that is coupled to the charging pad 32 for communicating with theguidance system 20. The beacon 96 is configured for transmitting awireless signal at a predetermined frequency (e.g., between 3 kHz and300 GHz), in response to instructions received from the externalcontroller 82 (shown in FIG. 2). The wireless signal is represented byspaced apart lines extending from the beacon 96 in FIG. 2. Thecontroller 24 may initiate communication with the external controller 82for activating the beacon 96. The controller 24 may include atransmitter (not shown) which transmits an activation signal to areceiver (not shown) of the external controller 82. Upon receipt of theactivation signal, the external controller 82 will “wake up”, if theexternal controller 82 is presently in a “sleep” mode, by energizingappropriate circuitry. The external controller 82 activates the beacon96 to begin transmitting. In one embodiment, the external controller 82activates the beacon 96 in response to a garage door (not shown) beingopened. In such an embodiment, a door sensor (not shown) may provide aninput signal to the external controller 82 that is indicative of agarage door position. Alternate embodiments of the guidance systemcontemplate that the external controller 82 may activate, or “wake up”in response to receiving input signals from another external device(such as a garage door opener); or that the beacon 96 transmitsconstantly and therefore does not need to “wake up”.

Referring to FIGS. 4 and 5, the vehicle 22 includes a plurality ofsensor arrays 98 for receiving the wireless signal from the beacon 96.The sensor arrays 98 are each secured proximate to the charging port 34.The sensor arrays 98 are secured in different locations depending on thetype of wireless signals received. For example, in one embodiment thesensor arrays 98 are configured for receiving an RF signal, andtherefore may be secured internally or within a protective housing (notshown). In other embodiments, the sensor arrays 98 are configured for IRcommunication, and therefore are externally mounted for receiving an IRsignal along a line-of-sight.

In the illustrated embodiment, the vehicle 22 includes three sensorarrays 98, which are generally referenced as: A1, A2 and A3. Each sensorarray 98 includes three sensors 100, according to one or moreembodiments. For example, sensor array A1 includes sensors: S1, S2, andS3 (not shown); sensor array A2 includes sensors: S4, S5, and S6 (notshown); and sensor array A3 includes sensors S7, S8, and S9 (shown inFIG. 5). Each sensor array 98 includes a micro-controller 102 forcommunicating with the sensors of the corresponding array 98. Eachsensor 100 transmits output, such as a time measurement signal(TIME_N_MSMT) to the corresponding microcontroller 102 that isindicative of the time at which the individual sensor 100 received thewireless signal from the beacon 96. The TIME_N_MSMT signal is an analogsignal according to one embodiment. Other embodiments contemplate asingle microcontroller 102 for communicating with all of the sensorarrays 98.

FIG. 5 depicts an enlarged view of sensor array A3, oriented relative tocharging pad 32. Each sensor 100 of an array 98 is equally spaced fromeach of the other sensors 100 within the array 98. For example, FIG. 5depicts sensor array A3 as having three sensors (S7, S8, and S9) whichare each equally spaced at one hundred-twenty degree intervals from eachother about a central axis 104. A coordinate system having four ninetydegree quadrants (I, II, III, and IV) is illustrated about the centralaxis 104.

Each microcontroller 102 determines the angular direction (θ) of thebeacon 96 relative to the corresponding sensor array 98. First themicrocontroller converts the analog TIME_N_MSMT signals into digitaldata (Tn). The microcontroller 102 includes signal conditioningequipment (not shown) for modifying any such received signals foranalysis. In one embodiment, the microcontroller 102 assigns a value ofzero to the first time signal that is received, and starts a timer. Themicrocontroller 102 then assigns a data value for each subsequentlyreceived time signal based on the time delay between the signals. Thedata values (Tn) correspond to the distance between each sensor 100 andthe beacon 96. As illustrated in FIG. 5, data value T7 corresponds tothe distance between sensor S7 and the beacon 96; data value T8corresponds to the distance between sensor S8 and the beacon 96; anddata value T9 corresponds to the distance between sensor S9 and thebeacon 96. The microcontroller 102 then compares the data value of thetime signals (Tn) to each other to determine which Quadrant the chargingpad 32 is located in, relative to the charging port 34 and to select atrigonometric equation from predetermined data for calculating theangular direction (θ).

For example, sensor S7 is oriented closest to the charging pad 32 inFIG. 5, and therefore S7 receives the wireless signal from the beacon 96before sensors S8 and S9. The microcontroller 102 receives TIME_7_MSMTfirst; assigns a data value of zero for T7; and starts a timer. SensorS8 is located closer to the charging pad 32 than sensor S9. Therefore,the microcontroller 102 would receive TIME_8_MSMT before TIME_9_MSMT;and assign a data value for T8 that is less than data value T9. Themicrocontroller 102 compares data values T7, T8 and T9 to predetermineddata. Since T7 equals zero, and T8 is less than T9, the microcontroller102 determines that the charging pad 32 is located in quadrant Irelative to the charging port 34.

The microcontroller 102 determines an angular direction (θ3) betweensensor array A3 and the charging pad 32 by comparing the data value forthe second (T8) and third (T9) received time signals. As illustrated inFIG. 6, the angular direction (θ) is measured from a transverse axis 105that extends through the centers of sensor arrays A2 and A3. The angulardirection (θ) between sensor array A1 and the charging pad 32, ismeasured relative to an axis (not shown) that is parallel to thetransverse axis 105. Equation 1 shown below provides an equation forcalculating the angular direction (θ3) when the charging pad 32 islocated in Quadrant I:

θ₃=sin⁻¹ [k*(T8+T9)]  Eq. 1

Equation 2 shown below represents a constant value (K) that is dependenton the placement of the sensors 100 about a circle having a radius (R)and the speed of light (c):

$\begin{matrix}{k = {0.5*\frac{c}{R}}} & {{Eq}.\mspace{14mu} 2}\end{matrix}$

For example, in one embodiment, the microcontroller 102 calculates θ3using Equations 1 and 2. First, the microcontroller 102 determines thatK equals 14.989*10̂9, using Equation 2, and substituting a value of 0.01meters for (R), and 299,792,458 meters/second for (c). Next, themicrocontroller 102 determines that (θ3) equals 60.0 degrees usingEquation 1 and substituting a value of 14.989*10̂9 for (K), 122nanoseconds for T8, and 456 nanoseconds for T9.

In one or more embodiments, the microcontroller 102 is configured withpredetermined data, or a “look-up” table for the angular directionvalues (θn). The predetermined data includes pre-calculated values forthe angular direction corresponding to various time data values (Tn) foreach of the four Quadrants (I, II, III, and IV). Thus after the guidancesystem 20 determines which Quadrant the charging pad 32 is located in;the microcontroller 102 compares the time values to predetermined data(look-up tables) to determine the angular direction.

FIGS. 6 and 7 depict schematic views of the sensor arrays of the vehicleguidance system 20, that are rotated approximately ninety degreesclockwise about central axis 104 when compared to FIG. 5. One of thesensor arrays (A3) may be disposed at the center of the charging port34. The beacon 96 is disposed at the center of the charging pad 32, andgenerally referenced by a star. By aligning the centers of the chargingport 34 and charging pad 32 to each other, there is a greater allowabletolerance between the two systems. Each sensor array: A1, A2 and A3includes a microcontroller (shown in FIG. 5) which transmits output,such as a corresponding angular direction signal DIR_θ1, DIR_θ2, andDIR_θ3, to the controller 24. Additionally, each sensor array 98 isequally spaced from each of the other sensor arrays 98, by a fixeddistance or “baseline”, which is generally referenced by letter “b” inFIG. 7.

The guidance system 20 utilizes the principles of triangulation todetermine the instantaneous position of the charging port 34 relative tothe charging pad 32, according to one or more embodiments. Triangulationis the process of determining the location of a point by measuringangles to it from known points at either end of a fixed baseline, ratherthan measuring distances to the point directly (trilateration). Thepoint can then be fixed as the third point of a triangle with one knownside and two known angles.

The controller 24 determines the distance (e) between the center of thecharging pad 32 (beacon 96) and the central axis 104 of the chargingport 34, using the angular direction values (θ2 and θ3) from knownpoints (A2 and A3) at either end of a fixed baseline (b). Since (θ2),(θ3), and distance (b) are known values, the controller 24 calculatesdistance (e) using trigonometry equations.

Equations 3 and 4 shown below provide equations for calculating distance(a) in FIG. 7 with respect to triangle (f, a, b), using a known valuefor distance (b), and an angular direction (θ2) that was calculated perEquation 1:

$\begin{matrix}{{\tan \; \theta_{2}} = \frac{a}{b}} & {{Eq}.\mspace{14mu} 3} \\{a = {b*\tan \; \theta_{2}}} & {{Eq}.\mspace{14mu} 4}\end{matrix}$

Equation 5 shown below provides an equation for calculating tan (θ2) inFIG. 7, with respect to triangle (f+g, d, b+c):

$\begin{matrix}{{\tan \; \theta_{2}} = \frac{d}{b + c}} & {{Eq}.\mspace{14mu} 5}\end{matrix}$

Equations 6 and 7 shown below provide equations for calculating distance(d) in FIG. 7, by combining Equations 3 and 5:

$\begin{matrix}{\frac{a}{b} = \frac{d}{b + c}} & {{Eq}.\mspace{14mu} 6} \\{d = \frac{a\left( {b + c} \right)}{b}} & {{Eq}.\mspace{14mu} 7}\end{matrix}$

Equations 8 and 9 shown below provide an equation for calculatingdistance (c) in FIG. 7, with respect to triangle (e, d, c):

$\begin{matrix}{{\tan \; \theta_{3}} = \frac{d}{c}} & {{Eq}.\mspace{14mu} 8} \\{c = \frac{d}{\tan \; \theta_{3}}} & {{Eq}.\mspace{14mu} 9}\end{matrix}$

Equations 10 and 11 shown below provide an equation for calculatingdistance (e) in FIG. 7, with respect to triangle (e, d, c):

$\begin{matrix}{{\cos \; \theta_{3}} = \frac{c}{e}} & {{Eq}.\mspace{14mu} 10} \\{e = \frac{c}{\cos \; \theta_{3}}} & {{Eq}.\mspace{14mu} 11}\end{matrix}$

Equations 12-15 shown below illustrate the steps substituting (d) fromEquation 7 into Equation 9 to form an equation for calculating distance(c) in terms of distances (a) and (b) and angular direction (θ3):

$\begin{matrix}{c = \frac{\frac{a\left( {b + c} \right)}{b}}{\tan \; \theta_{3}}} & {{Eq}.\mspace{14mu} 12} \\{c = {\frac{a}{\tan \; \theta_{3}} + \frac{a*c}{b*\tan \; \theta_{3}}}} & {{Eq}.\mspace{14mu} 13} \\{{c\left( {1 - \frac{a}{b*\tan \; \theta_{3}}} \right)} = \frac{a}{\tan \; \theta_{3}}} & {{Eq}.\mspace{14mu} 14} \\{c = \frac{\frac{a}{\tan \; \theta_{3}}}{1 - \frac{a}{b*\tan \; \theta_{3}}}} & {{Eq}.\mspace{14mu} 15}\end{matrix}$

Equation 16 shown below illustrates the step substituting (a) fromEquation 4 into Equation 15 to form an equation for calculating distance(c) in terms of distance (b) and angular directions (θ2) and (θ3):

$\begin{matrix}{c = \frac{\frac{b*\tan \; \theta_{2}}{\tan \; \theta_{3}}}{1 - \frac{b*\tan \; \theta_{2}}{b*\tan \; \theta_{3}}}} & {{Eq}.\mspace{14mu} 16}\end{matrix}$

Equation 17 shown below provides an equation for calculating distance(e) in terms of distance (b) and angular direction values (θ2) and (θ3)by substituting (c) from Equation 16 into Equation 11:

$\begin{matrix}{e = \frac{\frac{\frac{b*\tan \; \theta_{2}}{\tan \; \theta_{3}}}{1 - \frac{b*\tan \; \theta_{2}}{b*\tan \; \theta_{3}}}}{\cos \; \theta_{3}}} & {{Eq}.\mspace{14mu} 17}\end{matrix}$

The distance vector (V3) includes the distance value (e) and the angulardirection (θ3) between the charging port 34 and the charging pad 32. Theguidance system 20 calculates the angular direction (θ3) using Equation1, and the distance (e) using Equation 17. Equations 1-17 are applicablewhen the distance vector is located in Quadrant I, (when the beacon 96is closer to A1, than A2 or A3, and (θ2) is less than (θ3)). However, asimilar approach using trigonometric equations may be applied when thedistance vector is located in another Quadrant.

For example, in one embodiment the controller 24 receives input signals:DIR_θ1, which indicates that angular direction (θ1) equals 49.8 deg;DIR_θ2, which indicates that angular direction (θ2) equals 55.55 deg;and DIR_θ3, which indicates that angular direction (θ3) equals 60 deg.The controller 24 calculates distance (e) to be 5.35 m, using Equation17 and substituting a value for (b) of 1.0 m, a value for (θ2) of 55.55deg, and a value for (θ3) of 60 deg.

In one or more embodiments, the controller 24 is configured withpredetermined data, or a “look-up” table, for the distance vector. Thepredetermined data includes pre-calculated values for the distance valuecorresponding to various angular direction values, and distance (b) foreach of the four Quadrants (I, II, III, and IV). Thus after the guidancesystem 20 determines which Quadrant the charging pad 32 is located in,and the angular directions (θ1, θ2, and θ3); the controller 24 comparesthe angular direction values, and distance (b) to predetermined data(look-up tables) to determine the distance value.

With reference to FIGS. 4-8, a method for determining the instantaneousposition of a charging port 34 relative to the charging pad 32 isillustrated in accordance with one or more embodiments and is generallyreferenced by numeral 110. In operation 112, the controller 24 transmitsthe activation signal (WAKE_UP) to the external controller 82. Uponreceipt of the WAKE_UP signal, the external controller 82 instructs thebeacon 96 to begin transmitting the wireless signal (PULSE).

In operations 114, 116, and 118, each sensor 100 of a sensor array 98receives the PULSE signal and transmits a corresponding TIME_N_MSMTsignal to the microcontroller 102, that is indicative of the time atwhich the sensor 100 received the PULSE signal.

For example, in operation 114, each sensor (S1, S2, and S3) of array A1receives the PULSE signal and transmits a TIME_N_MSMT signal(TIME_1_MSMT, TIME_2_MSMT, and TIME_3_MSMT) to the microcontroller 102of A1 that is indicative of the time at which the sensor 100 receivedthe PULSE signal. In operation 116, each sensor (S4, S5, and S6) ofarray A2 receives the PULSE signal and transmits a TIME_N_MSMT signal(TIME_4_MSMT, TIME_5_MSMT, and TIME_6_MSMT) to the microcontroller 102of A2 that is indicative of the time at which the sensor 100 receivedthe PULSE signal. In operation 118, each sensor (S7, S8, and S9) ofarray A3 receives the PULSE signal and transmits a TIME_N_MSMT signal(TIME_7_MSMT, TIME_8_MSMT, and TIME_9_MSMT) to the microcontroller 102of A3 that is indicative of the time at which the sensor 100 receivedthe PULSE signal.

In operations 120, 122, and 124, each microcontroller 102 digitizes theTIME_N_MSMT signals, and transmits an angular direction signal (DIR_θn).The microcontroller 102 assigns a value of zero to the first time signalthat is received, and starts a timer. The microcontroller 102 thenassigns a data value for each subsequently received time signal based onthe time delay between the signals. The microcontroller 102 thencompares the data value of the time signals to each other to determinewhich Quadrant the charging pad 32 is located in and to select atrigonometric equation for calculating the angular direction (θn), frompredetermined data. Next, the microcontroller 102 calculates the angulardirection value (θn) and transmits a corresponding angular directionsignal (DIR_θn) to the controller 24.

For example, in operation 120, the microcontroller 102 of A1 receivesand digitizes input signals TIME_1_MSMT, TIME_2_MSMT, and TIME_3_MSMT toform data values T1, T2, and T3. Then the microcontroller 102 comparesT1, T2 and T3 to each other to select an equation for calculating θ1from predetermined data. Next the microcontroller 102 calculates θ1 andtransmits corresponding signal DIR_θ1 to the controller 24. In operation122, the microcontroller 102 of A2 receives and digitizes input signalsTIME_4_MSMT, TIME_5_MSMT, and TIME_6_MSMT to form data values T4, T5,and T6. Then the microcontroller 102 compares T4, T5 and T6 to eachother to select an equation for calculating θ2 from predetermined data.Next the microcontroller 102 calculates θ2 and transmits correspondingsignal DIR_θ2 to the controller 24. In operation 124, themicrocontroller 102 of A3 receives and digitizes input signalsTIME_7_MSMT, TIME_8_MSMT, and TIME_9_MSMT to form data values T7, T8,and T9. Then the microcontroller 102 compares T7, T8 and T9 to eachother to select an equation for calculating θ3 from predetermined data.Next the microcontroller 102 calculates θ3 and transmits correspondingsignal DIR_θ3 to the controller 24.

In operation 126, the controller 24 receives input signals DIR_1, DIR_2,and DIR_3 which correspond to angles θ1, θ2, and θ3 respectively. Thecontroller 24 then calculates the distance (e) between the charging pad32 and the charging port 34, using the angular direction values (On)from known points at either end of a fixed baseline (b). The controller24 then determines the distance vector (V3) by combining the distance(e) and angular direction (θ3).

In one or more embodiments, the vehicle guidance system 20 includesadditional operations for analyzing the charging status of the vehicle22. In operation 128, the controller 24 receives an input signal CHGfrom another vehicle controller that is indicative of the currentcharging status of the vehicle 22 (e.g., whether the vehicle 22 iscurrently charging or not). Next, the controller 24 transmits output,such as a vehicle status signal (VEH_STATUS) to the user interface 26that is indicative of both the distance vector (V3) and current chargingstatus (CHG). In operation 132, the user interface 26 receives theVEH_STATUS and conveys the information to the driver.

With reference to FIGS. 1, 9, and 10, the charging port 34 and chargingpad 32 must be generally close in proximity to each other for efficientinductive charging. Since the charging port 34 is not visible from thedriver's seat, it is difficult for the driver to align the charging port34 to the charging pad 32, without a guide or some type of feedback.Therefore, the user interface 26 conveys vehicle position information tothe user so that the user can align the charging port 34 to the chargingpad 32, without having to see either component.

FIG. 9 depicts the vehicle 22 in a non-aligned position, as the vehicle22 approaches the charging pad 32. FIG. 10 depicts the vehicle 22 asbeing aligned with the charging pad 32, and receiving electrical powerfrom the external power supply 28 (charging).

The user interface 26 receives the vehicle status signal from thecontroller 24 and displays a vehicle position indicator 138 and acharging status message 140. The driver uses this information as a guideto align the vehicle 22 relative to the external power supply 28. Theuser interface 26 is configured to display active images that adjust inreal time in response to the vehicle status signal.

The vehicle position indicator 138 includes elements that representinstantaneous positions, which are illustrated with solid lines in FIGS.9 and 10. The term “instantaneous” as used in the disclosure is arelative term because it is understood that there is some delay due tosignal processing and transmission. The vehicle position indicator 138includes a vehicle diagram 142 with a base element, such as chargingport element 144. The vehicle diagram 142 depicts an external outline ofthe vehicle 22; and represents an instantaneous vehicle position. Thecharging port element 144 represents an instantaneous charging portposition. The vehicle position indicator 138 also includes four wheelelements 146, according to one or more embodiments. Each wheel element146 represents an instantaneous wheel position.

The vehicle position indicator 138 also includes elements that representtarget positions, which are illustrated with phantom lines in FIGS. 9and 10. The vehicle position indicator 138 includes a target element 148that represents a target charging port position. The target element 148is indicative of a charging pad position, according to one or moreembodiments. Inductive charging of the vehicle battery is available whenthe charging port element 148 is aligned with the target element 148, orcharging pad 32. Other embodiments of the vehicle position indicator 138include target wheel elements and target vehicle diagrams (not shown)that represent corresponding target positions.

The user interface 26 is configured to display the charging statusmessage 140 in response to the vehicle status signal. The chargingstatus message 140 indicates whether or not the vehicle is presentlycharging. The charging status message 140 is conveyed as text within atext box in the illustrated embodiment. Other embodiments of the userinterface 26 contemplate a pictorial or audible charging status message.

The user interface 26 is further configured to display a steeringinstruction in response to the vehicle status signal, according to oneor more embodiments. The steering instruction informs the driver as towhich way to turn the steering wheel (shown in FIG. 3) to align thecharging port 34 with the charging pad 32.

The steering instruction is conveyed visually, as a pictorial element inthe vehicle position indicator 138, in one or more embodiments. In theillustrated embodiment, the steering instruction includes an arrow 152extending from one or more of the elements toward a corresponding targetelement. For example, an arrow 152 extends from the charging portelement 144 toward the target element 148. The arrow(s) 152 may alsoextend from an element, such as the front wheel elements 146, in thegeneral direction of where that element must move to align the chargingport 34 to the charging pad 32, as illustrated in FIG. 9. Otherembodiments of the steering instruction contemplate target wheelelements 154 (shown in FIG. 9) being disposed over a corresponding wheelelement 146 and rotated toward a target wheel position.

The steering instruction is conveyed visually, as text, in one or moreembodiments. In the illustrated embodiment, a steering instructionmessage 156 is displayed within a text box and adjacent to the chargingstatus message 140 on the user interface 26.

The user interface 26 is further configured to display a propulsioninstruction 158 that is conveyed to a driver in response to the vehiclestatus signal, according to one or more embodiments. The propulsioninstruction 158 informs the driver as to which direction to drive (e.g.,“Drive Forward”, as shown in FIG. 9), and when to stop driving (e.g.,“Stop Moving” as shown in FIG. 10). Other embodiments of the guidancesystem 20 include speakers (not shown) for conveying the steeringinstruction and/or the propulsion instruction to the driver audibly.

With reference to FIGS. 2, 9, and 10, one or more embodiments of theguidance system 20 are configured for vehicles 22 having a park assistfeature. For such vehicles, the driver controls the propulsion of thevehicle 22 via the driver control systems 84, and vehicle controllerscontrol the steering of the vehicle 22 using the power steering system86, for aligning the charging port 34 to the charging pad 32. The powersteering system 86 receives the VEH_STATUS signal, or another signalindicative of the distance vector between the charging port 34 andcharging pad 32, and controls the steering of the vehicle 22accordingly.

With reference to FIGS. 3 and 11, a simplified vehicle guidance systemis illustrated in accordance with another embodiment and is generallyreferenced by numeral 220. The guidance system 220 is depicted within avehicle 222. The guidance system 220 includes a controller 224 and auser interface, such as indicia 94 (shown in FIG. 3). The vehicle 222 isconfigured for inductive charging, and receiving electrical power from acharging pad 232 connected to an external power supply (not shown).

The vehicle 222 includes a charging port 234 that is aligned with thecharging pad 232 for receiving electrical power. The charging port 234is located at a defined lateral distance (“X”), and longitudinaldistance (“Y”) away from a reference wheel 240 of the vehicle 222. Thecharging pad 232 is located at a defined lateral distance andlongitudinal distance away from a wheel fixture 242, that is equal tothe lateral distance (X) and longitudinal distance (Y) between thecharging port 234 and the wheel 240. Thus aligning the wheel 240 to thewheel fixture 242 will also align the charging port 234 to the chargingpad 232. In one embodiment, the wheel fixture 242 includes a wheel chockfor engaging opposing sides of the wheel 240.

A wheel sensor 244 is disposed proximate the wheel fixture 242, andprovides a wheel position signal 246, that is indicative of the presenceof the reference wheel 240, according to one embodiment. The wheelsensor 244 may be a load sensor or a proximity switch, or other suitablesensor. An external controller 248 communicates with the charging pad232 and the wheel sensor 244. The external controller 248 instructs thecharging pad 232 to provide electrical power to the charging port 234 inresponse to the wheel signal 246. The charging pad 232 may be coupled toan actuator (not shown) to move relative to the charging port 34. Theexternal controller 248 may also control the actuator in response to thewheel signal 246. The controller 224 may communicate with the externalcontroller 248 for receiving input signals that are indicative of thevehicle position and charging status.

The user interface, or indicia 94 (shown in FIG. 3) communicates withthe controller 224 and is configured to display a vehicle positionindicator and a charging status message in response to the vehiclestatus signal. In one embodiment, the indicia 94 is illuminated whenboth the wheel 240 is secured in the wheel fixture 242, and the vehicleis charging.

Referring to FIG. 12, a method for conveying vehicle status informationto a driver for aligning a vehicle to an external power supply, isillustrated in accordance with one or more embodiments and is generallyreferenced by numeral 250. With reference to FIGS. 1, 11, and 12; inoperation 252, the controller 24, 224 determines if the charging port 34is aligned with the charging pad 32. In one or more embodiments, thecontroller 24 analyzes the distance vector (V3) to determine thisalignment. When the distance vector (V3) equals zero, the controllerdetermines that YES the charging port 34 is aligned with the chargingpad 32. In another embodiment, the controller 224 receives a wheelposition signal 246 from the external controller 248 that indicates thatthe reference wheel 240 is aligned with the wheel fixture 242. When thereference wheel 240 is aligned with the wheel fixture 242, thecontroller 224 determines that YES, the charging port 234 is alignedwith the charging pad 232.

In operation 254, after the controller 24 has determined that NO, thecharging port 34 is not aligned with the charging pad 32, the controllerdetermines the distance vector (V3). In one or more embodiments thecontroller 24 determines the distance vector (V3) using operations114-126 of method 110. In a simplified vehicle guidance system 220, thecontroller 224 waits for an updated wheel position signal 246.

In operation 256, after the controller 24, 224 has determined that NO,the charging port 34 is not aligned with the charging pad 32, thecontroller 24, 224 transmits an updated vehicle status signal(VEH_STATUS) to the user interface 26 or indicia 94. The user interface26 adjusts the information conveyed to the user (e.g., vehicle positionindicator, steering or propulsion instructions, and illumination) inresponse to the VEH_STATUS signal. After operation 256, the controller24, 224 returns to operation 252.

In operation 258, after the controller 24, 224 has determined that YES,the charging port 34 is aligned with the charging pad 32; the controller24, 224 transmits an updated vehicle status signal (VEH_STATUS) to theuser interface 26 or indicia 94. In operation 260, according to oneembodiment, the controller 224 illuminates the indicia 94 afterdetermining alignment is made (see FIG. 3). In operation 262, accordingto another embodiment, the controller 24 illustrates a charging portelement 144 overlaid upon a target element 148 after determiningalignment is made (see FIG. 10). In operation 264, according to yetanother embodiment of the vehicle guidance system 20 that coordinateswith a vehicle park-assist feature; the controller 24 transmits theVEH_STATUS signal to the power steering system 86, which ceases makingsteering adjustments when alignment is made.

While embodiments are described above, it is not intended that theseembodiments describe all possible forms of the invention. Rather, thewords used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

1. A vehicle guidance system comprising: a controller configured toreceive input indicative of a relative position between a charging portand a charging pad, and to provide output indicative of a distancevector therebetween in response to the input; and an interfacecommunicating with the controller and configured to display a baseelement representing the charging port and target element representingthe charging pad positioned relative to each other according to thedistance vector.
 2. The system of claim 1 wherein the charging port isintegrated with a vehicle, wherein the input comprises at least twodirection signals, wherein each direction signal is indicative of anangular direction between a location on the vehicle and a location ofthe charging pad, and wherein the controller triangulates the distancevector in response to the at least two direction signals.
 3. The systemof claim 1 wherein the interface displays the base element overlaid uponthe target element when the charging port is aligned with the chargingpad.
 4. The system of claim 1 wherein the distance vector isapproximately zero when the charging port is aligned with the chargingpad.
 5. The system of claim 2 further comprising at least two sensorarrays communicating with the controller, wherein each sensor array isconfigured to provide a direction signal indicative of an angulardirection between the sensor array and the charging pad and wherein thecontroller is further configured to provide the output indicative of thedistance vector in response to the direction signals.
 6. The system ofclaim 5 wherein the at least two sensor arrays comprise a first sensorarray and a second sensor array aligned with each other along atransverse axis and wherein an angular direction between the firstsensor array and the charging port and an angular direction between thesecond sensor array and the charging port are determined relative to thetransverse axis.
 7. The system of claim 5 wherein each sensor arrayfurther comprises at least two sensors each being configured to provideoutput indicative of a time when a signal was received from atransmitter electrically connected to the charging pad, and amicrocontroller communicating with the sensors and configured to providethe direction signal in response to the output indicative of the timeswhen the signals were received.
 8. The system of claim 7 wherein thesensors are internally mounted within a body of the vehicle andconfigured to receive a radio frequency (RF) wireless signal.
 9. Thesystem of claim 7 wherein the sensors are externally mounted upon a bodyof the vehicle and configured to receive an infrared (IR) wirelesssignal.
 10. A vehicle guidance system comprising: a sensor arraycomprising: at least two sensors each configured to provide outputindicative of a time when a signal was received from a transmitter, anda microcontroller communicating with the sensors and configured toprovide output indicative of an angular direction between the sensorarray and the transmitter, wherein the angular direction is based on adifference between the times when the signals were received.
 11. Thesystem of claim 10 further comprising: at least two sensor arrays eachbeing configured to provide output indicative of an angular directionbetween the sensor array and the transmitter; a controller incommunication with the sensor arrays and configured to provide outputindicative of a distance vector between at least one of the sensorarrays and the transmitter in response to the output indicative of theangular direction between the sensor array and the transmitter; and aninterface communicating with the controller and configured to display abase element representing a charging port and a target elementrepresenting a charging pad positioned relative to each other accordingto the distance vector.
 12. The system of claim 11 wherein thecontroller is further configured to provide an activation signal to anexternal controller, the external controller being electricallyconnected to the transmitter, and wherein the external controllerinstructs the transmitter to provide the signal in response to receivingthe activation signal.
 13. The system of claim 12 wherein the controlleris further configured to provide the activation signal in response to agarage door being opened.
 14. The system of claim 10 wherein themicrocontroller is further configured to compare the output indicativeof a time when a signal was received from a transmitter to predetermineddata to calculate the angular direction.
 15. A vehicle comprising: acharging port configured to receive an inductive charging current; atleast two sensor arrays, each configured to provide output indicative ofan angular direction between the sensor array and a transmitter remotefrom the vehicle; a controller configured to provide output indicativeof a distance vector between the charging port and the transmitter basedon the output indicative of the angular direction between the sensorarrays and transmitter; and an interface communicating with thecontroller and configured to display a base element representing thecharging port and a target element representing a charging padpositioned relative to each other according to the distance vector. 16.The vehicle of claim 15 further comprising a battery electricallyconnected to the charging port for storing electrical power
 17. Thevehicle of claim 15 wherein the charging port is electromagneticallycoupled to a charging pad of an external power supply during charging.18. The vehicle of claim 17 wherein the charging port comprises asecondary coil for receiving electrical power from a primary coil of thecharging pad during charging.
 19. The vehicle of claim 15 furthercomprising at least one electric motor configured to provide outputtorque for propelling the vehicle.
 20. The vehicle of claim 15 whereinthe charging port receives electrical power from an external powersupply having a solar panel.